Intelligent manual adjustment of an image control element

ABSTRACT

An imaging system comprises an image capturing device, a viewer, a control element, and a processor. The control element controls or adjusts an image characteristic of one of the image capturing device and the viewer. The processor is programmed to determine a depth value relative to the image capturing device, determine a desirable adjustment to the control element by using the determined depth value, and control adjustment of the control element to assist manual adjustment of the control element to the desirable adjustment. The processor may also be programmed to determine whether the adjustment of the control element is to be automatically or manually adjusted and control adjustment of the control element automatically to the desirable adjustment if the control element is to be automatically adjusted.

FIELD OF THE INVENTION

The present invention generally relates to imaging systems. Inparticular, it relates to an imaging system, and a method implementedtherein, for providing intelligent manual adjustment of a controlelement of either an image capturing device or a viewer to provideassistance in achieving a desirable adjustment of the control elementthat is a function of a depth value of a target area relative to theimage capturing device.

BACKGROUND OF THE INVENTION

Imaging systems such as a camera are commonly provided with an autofocus(AF) feature. As described in U.S. Pat. No. 7,782,392 B2, conventionalelectronic camera systems may provide an autofocus feature using eitherthe contrast (e.g., blur) of the captured image or a determined depthvalue of an object within the field of view of the camera. The depthvalue may be determined using reflected light and principles oftriangulation. In addition to providing an autofocus feature, automaticexposure control (AE) may also be provided to determine the brightnessof the object and adjust exposure. Alternatively, as described in U.S.Pat. No. 6,568,809 B2, a desirable focal point for a binocular or cameramay be determined by tracking the gaze of a user's eyes.

In certain applications, however, it may desirable to allow the user tooverride the autofocus (AF) and/or automatic exposure control (AE)feature. In this case, the user should be allowed to manually adjust acontrol element such as a focus or brightness control. When the image isout of focus, however, it may not be apparent to the user in whichdirection adjustment should be made. Accordingly, the user may adjustthe control in the wrong direction initially before realizing the errorand subsequently changing the direction of the adjustment.Alternatively, the user may adjust the control in the right direction,but overshoot the correct focal point so that a reversal of directionback to correct focal point is required. Such iterative type of manualadjustment, however, is time-consuming. Also, such iterative manualoperation of an image control element may require the complete attentionof the user so that the user is prevented from attending to other tasksat the time, such as when the camera is part of a robotic system and theuser is manipulating one or more tools, as described, for example, inU.S. Pat. No. 6,424,885 B1.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, one object of one or more aspects of the present inventionis an imaging system, and method implemented therein, that providesintelligent manual adjustment of an image control element.

Another object of one or more aspects of the present invention is animaging system, and method implemented therein, that provides userswitchable automatic and manual image control element adjustment modes.

Another object of one or more aspects of the present invention is animaging system, and method implemented therein, that encourages a userto manually adjust a control element towards a desirable adjustmentand/or discourages or prevents a user from manually adjusting thecontrol element away from the desirable adjustment.

Another object of one or more aspects of the present invention is animaging system, and method implemented therein, that determinesdesirable adjustments to an image control element based upon a depthvalue for a target area relative to an image capturing device.

These and additional objects are accomplished by the various aspects ofthe present invention, wherein briefly stated, one aspect is a methodfor intelligent manual adjustment of a control element. The methodcomprises: determining a depth value of a target area relative to theimage capturing device; determining a desirable adjustment to a controlelement for controlling an image characteristic of one of the imagecapturing device and a viewer by using the determined depth value,wherein the viewer is displaying images derived from the image capturingdevice; and controlling adjustment of the control element to assistmanual adjustment of the control element to the desirable adjustment.

Another aspect is an imaging system comprising: an image capturingdevice; a viewer displaying images derived from the image capturingdevice; a control element for controlling an image characteristic of oneof the image capturing device and the viewer; and a processor. Theprocessor is programmed to: determine a depth value of a target arearelative to the image capturing device; determine a desirable adjustmentto the control element by using the determined depth value; and controladjustment of the control element to assist manual adjustment of thecontrol element to the desirable adjustment.

Additional objects, features, and advantages of the various aspects ofthe present invention will become apparent from the followingdescription which should be taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of an imaging system utilizingaspects of the present invention.

FIG. 2 illustrates a flow diagram of a method for intelligent manualadjustment of an image control element utilizing aspects of the presentinvention.

FIG. 3 illustrates a schematic of the stereo geometry for two imagecapturing elements of an imaging system utilizing aspects of the presentinvention.

FIG. 4 illustrates a stereo view as seen in a stereo viewer of animaging system utilizing aspects of the present invention.

FIG. 5 illustrates a schematic of positions of a focal point along adepth axis relative to a desired focal point as may be experienced in animaging system utilizing aspects of the present invention.

FIG. 6 illustrates a schematic of a manually rotatable control elementof an imaging system utilizing aspects of the present invention.

FIG. 7 illustrates a top view of an operating room employing a medicalrobotic system including an imaging system utilizing aspects of thepresent invention.

FIG. 8 illustrates a side view of a patient-side cart usable in amedical robotic system including an imaging system utilizing aspects ofthe present invention.

FIG. 9 illustrates a perspective view of an instrument usable in amedical robotic system including an imaging system utilizing aspects ofthe present invention.

FIG. 10 illustrates a front view of an operator console usable in amedical robotic system including an imaging system utilizing aspects ofthe present invention.

FIG. 11 illustrates a block diagram of the medical robotic systemincluding an imaging system utilizing aspects of the present invention.

FIG. 12 illustrates master control device reference frames andcorresponding degrees of freedom in a medical robotic including animaging system utilizing aspects of the present invention.

FIG. 13 illustrates a camera control reference frame and correspondingdegrees of freedom in a medical robotic including an imaging systemutilizing aspects of the present invention.

DETAILED DESCRIPTION

FIG. 1 illustrates, as an example, a block diagram of an imaging system1000. An image capturing device 1010 is included, which is preferably ahigh-definition digital stereo camera that generates a video stream ofstereo images captured at a frame rate of the camera, such as thirtyframes per second. Each frame of stereo images includes a left stereoimage and a right stereo image. An example of such a stereo camera isdescribed below in reference to FIGS. 7, 8. Alternatively, the imagecapturing device 1010 may be a monovision camera or it may be a deviceusing a different imaging modality such as radiography, ultrasound, andmagnetic resonance imaging. Although only one image capturing device isshown, the imaging system 1000 may include a plurality of imagecapturing devices of the same or different types.

A viewer 1020 is included, which is preferably a stereo viewer havingleft and right display screens for respectively displaying left andright stereo images derived from left and right stereo images capturedby the image capturing device 1010. An example of such a stereo vieweris described below in reference to FIG. 10. Alternatively, if the imagecapturing device 1010 is not a stereo camera, then the viewer 1020 maybe monovision viewer suitable for displaying monovision and/or othertypes of images captured by the image capturing device 1010.

A processor 1030 is included, which performs various functions for theimaging system 1000. For example, the processor 1030 may process theimages received from the image capturing device 1010 for display on theviewer 1020. Such processing may include modification of the capturedimages for different resolutions and for camera distortion and/ormisalignment correction. In telerobotic operation, such processing mayalso include modification of the captured images to providetelepresence.

The processor 1030 also performs a method 2000 as described below inreference to FIG. 2. In doing so, the processor 1030 processes userinputs received from various input devices such as input devices 1031,1032, a Graphical User Interface (GUI) 1041, a telestrator 1043, aplurality of control elements (e.g., 1011, 1012, 1013) associated withthe image capturing device 1010 for adjusting image characteristics orattributes of the captured images, and a plurality of control elements(e.g., 1021, 1022, 1023) associated with the viewer 1020 for adjustingimage characteristics or attributes of the displayed images.

Also while performing the method 2000, the processor 1030 may receiveinformation from various sources, such as the input devices 1031, 1032,a gaze tracker 1043, and the memory 1033. The processor 1030 may alsogenerate outputs which it transmits to various devices such as audiooutput transmitted to a speaker 1042 and haptic or force feedbacktransmitted to input devices 1031, 1032 and control elements 1011, 1012,1013, 1021, 1022, 1023 as sensory outputs. The input devices 1031, 1032may be manually manipulatable like the control elements or they mayprovide a means for the user to interact with the processor 1030 such asa keyboard or mouse. Alternatively, one or both of the input devices1031, 1032 may respond to other user initiated stimuli such as voicecommands. Although only two input devices are shown in FIG. 1, it is tobe appreciated that more or less input devices may be included in theimaging system 1000.

Additional details on a telestrator such as the telestrator 1044 may befound, for example, in U.S. 2007/0156017 entitled “Stereo Telestrationfor Robotic Surgery”, which is incorporated herein by reference.Additional details on such a gaze tracker such as the gaze tracker 1043may be found, for example, in U.S. Application No. 61/554,741 entitled“Method and System for Stereo Gaze Tracking”, which is incorporatedherein by reference.

FIG. 2 illustrates, as an example, a flow diagram of a method 2000 forintelligent manual adjustment of an image control element. The method ispreferably implemented as program code stored non-transitorily in memory1033 and executed by the processor 1030. The image control element maybe one of the control elements 1011, 1012, 1013 of the image capturingdevice 1010 or it may be one of the control elements 1021, 1022, 1023 ofthe viewer 1020.

Although the following description of the method describes adjustment ofa single control element as a function of a depth value of a target arearelative to an image capturing device, it is to be appreciated that themethod may be extended and used to control any combination of multiplecontrol elements as functions of multiple depth values for multipletarget areas relative to multiple image capturing devices. FIGS. 3-13are provided herein as part of, or to clarify with examples, thedescription of the method.

In block 2001, the method receives an indication of a target area (alsoreferred to as a “region of interest”). As used herein, the target areamay refer to an area in an image captured by the image capturing device1010 as well as its corresponding area being displayed on the viewer1020. Whether the term refers to a captured image or its correspondingdisplayed image should be clear from its contextual use. Althoughreferred to as being an “area”, the target area for stereovision isgenerally three-dimensional in shape and extends within a stereo view ofthe image capturing device to a surface topology of one or more objects.

The target area may be predefined as a default area in the images or itmay be user defined or overridden. For example, the default area may bedefined as a central area in the field of view of the image capturingdevice. As another example, the default area may be defined as an areaon an object, wherein a central point of the area intersects a centralline of sight of the image capturing device.

As an example of the user specifying a target area, the user may specifythe target area on the viewer 1020 by interacting with the GUI 1041. Asanother example, the user may specify the target area by commandingmovement of a cursor on the display screen of the viewer 1020 using amouse and providing an indication that an area circumscribed by themovement of the cursor is to be selected as a target area by clicking abutton on the mouse. When the target area is defined relative to thedisplay screen of the viewer 1020, conventional transformationtechniques are usable to translate the specified target area on theviewer 1020 to a corresponding target area in a reference frame definedby the image capturing perspective of the image capturing device 1010.For additional details on such reference frame transformations, see,e.g., U.S. 2012/0290134 A1 entitled “Estimation of a Position andOrientation of a Frame Used in Controlling Movement of a Tool,” which isincorporated herein by reference.

As another example of the user specifying a target area, the user mayspecify the target area by using the telestrator 1044. As anotherexample, the user may define the center of a target area using the gazetracker 1043 which tracks the user's gaze point on the display screen ofthe viewer 1020. In this case, the user may select a target area byissuing a command to do so using, for example, one of the input devices1031, 1032, wherein the center of the target area is the current gazepoint and its area may be predefined or definable by the user using anyconventional means such as the GUI 1041.

Regardless of how the target area is defined, it may be displayed forthe convenience of the user on the viewer 1020 at its proper location asan overlay to any three-dimensional objects or surface topology beingdisplayed thereon at the time. The overlay may be a three-dimensionaloverlay at the same depths and following the contour of the underlyingobjects or surface topology or it may be a two-dimensional overlayfloating over the underlying objects or surface topology at a specifieddepth value.

In block 2002, the method determines the depth value for the target areain the stereo images using one or a combination of known methods. As anexample, a structured light technique may be used in which a known lightpattern is projected onto the target area and the relative lightintensities on the scene tracked to derive a depth map for the scene.See, e.g., Daniel Scharstein and Richard Szeliski, “High-Accuracy StereoDepth Maps Using Structured Light,” IEEE Computer Society Conference onComputer Vision and Pattern Recognition (CVPR 2003), vol. 1, pages195-202, Madison, Wis., June 2003. As another example, the depth valuemay be determined by determining corresponding points in stereo imagesusing a robust sparse image matching algorithm, determining disparitiesbetween the corresponding points, and converting the disparities todepths using a predetermined disparity to depth mapping. See, e.g., U.S.Pat. No. 8,184,880 entitled “Robust Sparse Image Matching for RoboticSurgery”, which is incorporated herein by reference. As yet anotherexample, a laser range finder may be used for determining depth valuesof a three-dimensional scene. The depth value may be an average depthvalue for the surface topology of the target area. Alternatively, thedepth value may be a minimum depth value for the surface topology of thetarget area. When tools, which are being used to interact with objectsof the surface topology, appear above the surface topology, depth valuesfor the tools which occlude part of the surface topology may be includedor excluded from the calculation.

As an example of the depth value, FIG. 3 illustrates a schematic of thestereo geometry for two image capturing elements, e.g., left and rightoptical lens 101, 102, which are separated by a baseline distance “b”.Left and right image planes 121, 122 are shown at a focal length “f”(i.e., a depth at which the left and right images are focused). Theimage planes 121, 122 represent stereo images that are captured by thelens 101, 102 and are bounded by their fields of view. The focal lengthmay be adjusted within a focusing range, but the baseline distance isfixed for the stereoscopic camera.

A point “P” at a depth “Z” from the lens 101, 102 is seen at differentpoints on the image planes 121, 122. In particular, the point “P” isprojected at a position “d1” on the left image plane 121 and projectedat a position “d2” on the right image plane 122. The difference ordisparity “D” between the two positions “d2” and “d1” can be determinedfrom the following well-known relationship:

$\begin{matrix}{\frac{D}{b} = \frac{f}{Z}} & (1)\end{matrix}$

Thus, as the depth “Z” gets smaller and smaller, the disparity “D” getslarger and larger.

Stereo images captured by the stereoscopic camera are displayable on astereo viewer. As an example, the stereo viewer may have left and rightdisplay screens upon which left and right stereo images are respectivelydisplayed. The stereo viewer in this case, may also have left and righteyepieces through which a user places his/her left and right eyes torespectively view the left and right display screens.

Although use of a single target area is described above, it is to beappreciated that a plurality of target areas, each indicating adifferent area of interest, may be defined by a user and used in themethod. In such case, one of the target areas may be selected forprocessing as described above. Alternatively, depth values may bedetermined for each of the plurality of target areas. In thisalternative case, one of the depth values may then be selected andprocessed as described above or the depth values for a combination oftarget areas may be used instead, such as an average of the depthvalues. As an example of such a plurality of target areas, FIG. 4illustrates a plurality of user specified target areas (e.g., 411, 412,413) which have been defined relative to one or more objects (e.g., 401,402) as seen on a two-dimensional or three-dimensional display screen400 of the viewer 1020.

In block 2003, the method determines whether the depth value is lessthan a threshold depth value at which point an adjustment to the controlelement is desirable. The threshold depth value may be empiricallydetermined and pre-programmed into or stored in the memory 1033 of theimaging system 1000 as a default value, such as three centimeters whichhas been empirically determined to be suitable for a medical roboticsystem as described in reference to FIGS. 7-10. Alternatively, thethreshold depth value may be a function of a characteristic of an imagecaptured by the image capturing device 1010. Additionally, oralternatively, it may be specified and/or altered by the user in aconventional manner to accommodate specific user preferences.

Although use of a single threshold depth value is described above, it isto be appreciated that a plurality of threshold depth values may be usedin the method. For example, each threshold depth value may correspond toa different desirable adjustment for a control element. Alternatively,each threshold depth value may correspond to a desirable adjustment fora different control element.

If the determination in block 2003 is NO, then the method jumps back toblock 2002 and loops through blocks 2002, 2003 until either a YESdetermination results in block 2003 or the method is turned OFF througha mode switch or some other means. If the determination in block 2003 isYES, the method proceeds to block 2004.

In block 2004, the method determines a desirable adjustment for thecontrol element. As an example, the method may determine the desirableadjustment by using an empirically determined equation which is afunction of depth values. The equation in this case may be included inprogram code stored in memory 1033 and executed by the processor 1030.As another example, the method may determine the desirable adjustment byusing a Look-Up Table (LUT) of empirically determined values which isindexed by depth values. The LUT in this case may be stored in memory1033 and accessed by the processor 1030 when performing the method. Whenusing the LUT, a linear or best curve fitting interpolation betweenlook-up table values may also be performed as necessary. Also, whenusing the LUT, the method may process the information read from the LUTby adjusting the information according to predefined and/or userspecified preferences. Either or both the threshold value which is beingused and the desirable adjustment which is being determined depend uponthe characteristic of the image which is being adjusted by the controlelement. Typical controllable image characteristics include brightness,focus, contrast, resolution, color balance, and sharpness. These andother controllable characteristics of the image captured by the imagecapturing device 1010 or the image displayed on the viewer 1020 are tobe included within the scope of the method.

As an example, when the image capturing device is a camera and thecharacteristic being controlled is the brightness of the captured image,the control element is the brightness control of the camera. In thiscase, the brightness control may be coupled to, or comprise, anadjustable gain of an image sensor of the camera or the brightnesscontrol may be coupled to, or comprise, an adjustable power output foran illuminator of the camera. The adjustment to the brightness controlmay be determined by the method using a function in which the brightnesslevel monotonically decreases as the depth value changes from thethreshold depth value to a minimum depth value (i.e., at very closerange to the camera). The rate at which the brightness levelmonotonically decreases as the depth value changes from the thresholdlevel to the minimum depth value may in this case be a function of acharacteristic of the image captured by the camera. The characteristicbeing used in this case, may be any suitable one of the imagecharacteristics previously mentioned.

As another example, when the image capturing device is a camera and thecharacteristic being controlled is the focus of the captured image, thecontrol element may be a manually rotatable control, such as a knob ordial, which is used to adjust the focus of the camera. In this case, thedesirable adjustment to the focus control may be determined as afunction of a focal point of the camera and the depth value of thetarget area relative to the camera. In addition, an image characteristicof a captured image may be determined by the method and the desirableadjustment to the control element may be determined by modulating theoutput of a function of the depth value of the target area by thedetermined image characteristic.

In block 2005, the method determines whether it is operating in a manualmode. As an example, the default mode for the imaging system 1000 may beto perform an autofocus function. In this case, a manual over-ride mustbe activated by the user in order for the user to manually focus theimage capturing device. Alternatively, the default mode for the imagingsystem 1000 may be the manual mode. In this latter case, the user mustdo something to initiate the autofocus mode such as depressing a buttonpartially down such as on a camera. If the determination in block 2005is YES, then the method proceeds to block 2006 where the method providesassistance to the user to manually adjust the control element to thedesirable adjustment of the control element. On the other hand, if thedetermination in block 2005 is NO, then the method proceeds to block2007 where the method automatically adjusts the control element to thedesirable adjustment of the control element.

An example of processing performed by the method in block 2006 follows.If the image capturing device is a camera, if the characteristic beingcontrolled is the focus of the captured image, and if the controlelement is a manually rotatable control, then in addition to determiningthe desirable adjustment to the focus control as previously described, adirection to the desirable adjustment may also be determined in block2004. In this case, the direction of the adjustment may be determined bythe direction that the camera is moving at the time relative to thetarget area.

In particular, if prior to the movement, the focal point of the camerawas properly adjusted to the depth value of the target area (i.e., adepth value which is referred to herein as the “Desired Focal Point”),then moving the camera towards the target area would result in movingthe camera's focal point past the Desired Focal Point, such as the pointdesignated as the “Long Focal Point” in FIG. 5. On the other hand,moving the camera back away from the target area would result in movingthe focal point short of the Desired Focal Point, such as the pointdesignated as the “Short Focal Point” in FIG. 5. Thus, the desirableadjustment of the focus control would result in moving a Long FocalPoint back to the Desired Focal Point and moving a Short Focal Pointforward to the Desired Focal Point, as shown by the arrows designated“Direction of Desirable Adjustment” in FIG. 5. In contrast, anundesirable adjustment of the focus control would result in movingfurther away from the Desired Focal Point, as shown by the arrowsdesignated “Direction of Undesirable Adjustment” in FIG. 5.

The direction in which the camera is moving may be readily determined ifthe camera is moved by a robotic arm, such as described in reference tothe endoscope of the medical robotic system 7000 of FIGS. 7-10. In thatcase, the direction of the camera movement may be determined byreceiving sensor information indicating positions of joints of therobotic arm and determining the movement of the camera by applying thesensor information to forward kinematics of the robotic arm.

Continuing with the example for block 2006, the method controlsadjustment of the control element to assist manual adjustment of thecontrol element to the desirable adjustment by providing assistance tomanually adjust the focus control according to the determined directionand the amount of the desirable adjustment determined in block 2004. Oneway such assistance may be provided is to define a rotation direction ofa manually rotatable control to always correspond to moving the focalpoint towards the depth value of the target area and an oppositerotation direction of the manually rotatable control to alwayscorrespond to moving the focal point away from the depth value of thetarget area. As an example, the method may provide assistance tomanually adjust the focus control by defining a Clockwise Rotation ofthe manually rotatable control element 601 (as shown in FIG. 6) asalways resulting in moving the focal point towards the Desired FocalPoint in the Direction of Desirable Adjustment (as shown in FIG. 5) anddefining a Counter-Clockwise Rotation of the manually rotatable controlelement 601 (as shown in FIG. 6) as always resulting in moving the focalpoint away from the Desired Focal Point in the Direction of UndesirableAdjustment (as shown in FIG. 5). In this case, the user does not need toknow whether the focal point of the camera is short or long of theDesired Focal Point. In either case, a Clockwise Rotation of the of themanually rotatable control element 601 will drive the focal pointtowards the Desired Focal Point.

Still continuing with the example for block 2006, another way suchassistance may be provided is to define a rotation direction of amanually rotatable control that the user first takes as corresponding tomoving the focal point towards the depth value of the target area and anopposite rotation direction of the manually rotatable control ascorresponding to moving the focal point away from the depth value of thetarget area. As an example, the method provides assistance to manuallyadjust the focus control by defining a Clockwise Rotation of themanually rotatable control element 601 (as shown in FIG. 6) as resultingin moving the focal point towards the Desired Focal Point in theDirection of Desirable Adjustment (as shown in FIG. 5) if the user firstrotates the manually rotatable control element 601 in the clockwisedirection while the method is performing block 2006. In this case, ifthe user subsequently rotates the manually rotatable control element 601in the counter-clockwise direction while the method is performing block2006, it will result in the focal point moving in the Direction of theUndesirable Adjustment (as shown in FIG. 5). Conversely, if the userfirst rotates the manually rotatable control element 601 in thecounter-clockwise direction while the method is performing block 2006,then the method provides assistance to manually adjust the focus controlby defining a Counter-Clockwise Rotation of the manually rotatablecontrol element 601 (as shown in FIG. 6) as resulting in moving thefocal point towards the Desired Focal Point in the Direction ofDesirable Adjustment (as shown in FIG. 5). In this latter case, if theuser subsequently rotates the manually rotatable control element 601 inthe clockwise direction while the method is performing block 2006, itwill result in the focal point moving in the Direction of theUndesirable Adjustment (as shown in FIG. 5).

For additional assistance in manually adjusting the control element tothe desirable adjustment in block 2006, the method may provide a sensoryindication when the focal point of an image capturing device, such as acamera, coincides with the target point. The sensory indication may beone or more of a visual indication on the viewer 1020, an auditoryindication on the speaker 1042, and a force feedback on the manuallyrotatable control element 601. The force feedback is preferably a hapticforce on the control element that nudges the user to move the controlelement to the desirable adjustment so that the focal point of theimaging device is moved to coincide with the depth value of the targetarea. In such case, the haptic force may decrease in magnitude as thefocal point of the imaging device moves closer towards the Desired FocalPoint and may increase in magnitude as the focal point of the imagingdevice moves further away from the Desired Focal Point.

Automatic processing such as performed by the method in block 2007 isrelatively straightforward. Examples of such automatic processinginclude the autofocus and automatic exposure functions on a camera.Basically, they simply entail controlling adjustment of the controlelement automatically to the desirable adjustment if the control elementis to be automatically adjusted.

FIGS. 7-10 illustrate, as an example, a medical robotic system 7000 inwhich the method 2000 may be implemented and the imaging system 1000 maybe included. FIG. 7 illustrates a top view of an operating room in whichthe medical robotic system 7000 is being employed by a Surgeon (“S”) toperform a medical procedure on a Patient (“P”). The medical roboticsystem in this case is a Minimally Invasive Robotic Surgical (MIRS)system including a Console (“C”) utilized by the Surgeon whileperforming a minimally invasive diagnostic or surgical procedure on thePatient with assistance from one or more Assistants (“A”) while thePatient is on an Operating table (“O”). The medical robotic system 7000may include the imaging system 1000 or it may be considered a particularexample of the imaging system 1000.

The Console, as further described in reference to FIG. 10, includes aprocessor 43 which communicates with a movable cart 150 over a bus 110.A plurality of robotic arms 34, 36, 38 are included on the cart 150. Atool 33 is held and manipulated by robotic arm 36, another tool 35 isheld and manipulated by robotic arm 34, and an endoscope 37 is held andmanipulated by robotic arm 38. In this example, each of the tools 33, 35and the endoscope 37 is introduced through its own entry aperture in thePatient. As an example, tool 33 is inserted into aperture 166 to enterthe Patient.

The Surgeon performs the medical procedure by manipulating the inputdevices 41, 42 so that the processor 43 causes their respectivelyassociated robotic arms 34, 36 to manipulate their respective removablycoupled tools 33, 35 accordingly while the Surgeon views real-timeimages of a work site in three-dimensions (“3D”) on a stereo visiondisplay 45 of the Console. A stereoscopic endoscope 37 (having left andright cameras for capturing left and right stereo views) captures stereoimages of the work site. The processor 43 processes the stereo images sothat they may be properly displayed on the stereo vision display 45.

Each of the robotic arms 34, 36, 38 is conventionally formed of links,such as link 162, which are coupled together and manipulated throughactuatable joints, such as joint 163. Each of the robotic arms includesa setup arm and a slave manipulator. The setup arm positions its heldtool so that a pivot point occurs at its entry aperture into thePatient. The slave manipulator may then manipulate its held tool orendoscope so that it may be pivoted about the pivot point, inserted intoand retracted out of the entry aperture, and rotated about its shaftaxis. The robotic arms 34, 36, 38 may be carted into the operating roomvia the cart 150 or alternatively, they may be attached to sliders on awall or ceiling of the operating room.

FIG. 8 illustrates a front view of the cart 150. In addition to therobotic arms 34, 36, 38, shown in FIG. 7, a fourth robotic arm 32 isshown in FIG. 8. The fourth robotic arm 32 is available so that anothertool 31 may be introduced at the work site along with the tools 33, 35and endoscope 37.

FIG. 9 illustrates an exemplary tool 100 that may be used for eithertool 33 or 35. The tool 100 comprises an interface housing 108, a shaft104, an end effector 102, and a wrist mechanism 106 which includes oneor more wrist joints. The interface housing 108 is removably attached toa robotic arm so as to be mechanically coupled to actuators (such asmotors) in the slave manipulator of the attached robotic arm. Cables orrods, that are coupled to the actuators of the slave manipulator andextend through the shaft 104 from the interface housing 108 to the oneor more wrist joints of the wrist mechanism 106 and to the jaws of thetool's end effector 102, actuate the wrist joints and jaws in aconventional manner. The slave manipulator may also manipulate the toolin pitch and yaw angular rotations about its pivot point at the entryaperture, manipulate the tool in a roll angular rotation about thetool's shaft axis, and insert and retract the tool along a rail on therobotic arm as commanded by the processor 43.

FIG. 10 illustrates, as an example, a front view of the Console usablein the medical robotic system 1000. The Console has left and right inputdevices 41, 42 which the user may grasp respectively with his/her leftand right hands to manipulate associated devices, such as the tools 33,35, in preferably six degrees-of-freedom (“DOF”). Foot pedals 44 withtoe and heel controls are provided on the Console so the user maycontrol movement and/or actuation of devices associated with the footpedals. A processor 43 is provided in the Console for control and otherpurposes. The stereo vision display 45 is provided so that the user mayview the work site in stereo vision from images captured by thestereoscopic camera of the endoscope 37. Left and right eyepieces, 46and 47, are provided in the stereo vision display 45 so that the usermay view left and right two-dimensional (“2D”) display screens insidethe display 45 respectively with the user's left and right eyes.

The processor 43 performs various functions in the medical roboticsystem. One important function that it performs is to translate andtransfer the mechanical motion of input devices 41, 42 through controlsignals over bus 110 to command actuators of their associated roboticarms to actuate their respective joints so that the Surgeon caneffectively manipulate devices, such as the tools 33, 35, and endoscope37. Another function is to perform the method 2000 as well as implementvarious controllers and/or other methods described herein. Althoughdescribed as a processor, it is to be appreciated that the processor 43may be implemented by any combination of hardware, software andfirmware. Also, its functions as described herein may be performed byone unit or divided up among different components, each of which may beimplemented in turn by any combination of hardware, software andfirmware. Further, although being shown as part of or being physicallyadjacent to the Console, the processor 43 may also comprise a number ofsubunits distributed throughout the system.

U.S. Pat. No. 6,659,939 B2 entitled “Cooperative Minimally InvasiveTelesurgical System,” which is incorporated herein by reference,provides additional details on a medical robotic system such asdescribed herein.

FIG. 11 illustrates, as an example, a block diagram of components forcontrolling and selectively associating device manipulators to themaster controls 108, 109. Various surgical tools such as graspers,cutters, and needles may be used to perform a medical procedure at awork site within the Patient. In this example, two surgical tools 138,139 are used to robotically perform the procedure and the camera 140 isused to view the procedure.

Each of the medical devices 138, 139, 140 is manipulated by its ownmanipulator. In particular, the camera 140 is manipulated by a cameramanipulator (ECM) 212, the first surgical tool 139 is manipulated by afirst tool manipulator (PSM1) 232, and the second surgical tool 138 ismanipulated by a second tool manipulator (PSM2) 242.

In this example, each of the master controls 108, 109 may be selectivelyassociated with either the camera 140 or one of the surgical tools 138,139 so that the associated device may be controlled by the input devicethrough its controller and manipulator. For example, by placing switches258, 259 in their respective tool following modes “T2” and “T1”, theleft and right master controls 108, 109 may be respectively associatedwith the surgical tools 139, 138, which are telerobotically controlledthrough their respective controllers 233, 243 and manipulators 232, 242so that the Surgeon may perform a medical procedure on the Patient whilethe camera 140 is soft-locked in place by its controller 213.

When the camera 140 is to be repositioned by the Surgeon, either one orboth of the left and right master controls 108, 109 may be associatedwith the camera 140 so that the Surgeon may move the camera 140 throughits controller 213 and manipulator 212. In this case, the disassociatedone(s) of the surgical tools 138, 139 is/are soft-locked in place byits/their controller(s). For example, by placing switches 258, 259respectively in camera positioning modes “C2” and “C1”, the left andright master controls 108, 109 may be associated with the camera 140,which is telerobotically controlled through its controller 213 andmanipulator 212 so that the Surgeon may position the camera 140 whilethe surgical tools 138, 139 are soft-locked in place by their respectivecontrollers 233, 243. If only one input device is to be used forpositioning the camera, then only one of the switches 258, 259 is placedin its camera positioning mode while the other one of the switches 258,259 remains in its tool following mode so that its respective inputdevice may continue to control its associated surgical tool.

The selective association of the master controls 108, 109 to otherdevices in this example may be performed by the Surgeon using aGraphical User Interface (GUI), a voice recognition system, or any otherconventional manner operable through the Surgeon Console. Alternatively,the association of the master controls 108, 109 may be changed by theSurgeon depressing a button on one of the master controls 108, 109 ordepressing the foot pedal 105, or using any other well known modeswitching technique.

One application in which the present invention is particularly useful iswhen the switches 258, 259 are both placed in their respective camerapositioning modes “C2” and “C1” and an “image referenced control” schemeis employed to control Surgeon positioning and orienting of the camera'stip using the master controls 108, 109 in a “virtual handlebar” fashion.

FIG. 12 illustrates, as an example, reference frames and correspondingdegrees-of-freedom for the master controls 108, 109. Each of the mastercontrols 108, 109 has a respective pivot point 302, 312 (also referredto as a “control point”) and a reference frame centered at the pivotpoint. The master controls 108, 109 provide three translationaldegrees-of-freedom movement (e.g., forward/back along their respectivelongitudinal axes X_(LM), X_(RM) of their grippers 301, 311;side-to-side along first axes Y_(LM), Y_(RM) orthogonal to thelongitudinal axes X_(LM), X_(RM); and up/down along second axes Z_(LM),Z_(RM) orthogonal to the first axes Y_(LM), Y_(RM) and longitudinal axesX_(LM), X_(RM)) relative to their respective pivot points 302, 312 oftheir grippers 301, 311. The master controls 108, 109 also provide threeorientational degrees-of-freedom movement (e.g., roll about theirrespective longitudinal axes X_(LM), X_(RM); pitch about theirrespective first axes Y_(LM), Y_(RM); and yaw about their respectivesecond axes Z_(LM), Z_(RM)) relative to their respective pivot points302, 312 of their grippers 301, 311. In addition, squeezing theirrespective grippers 301, 311 may provide additional degrees-of-freedomfor manipulating end effectors of surgical tools respectively associatedwith the master controls 108, 109 when in tool following mode.

In this example, both master controls 108, 109 are used to move thecamera 140 as the Surgeon views images captured by the camera 140. Thus,an “image referenced control” is used in which the Surgeon is given theimpression that he or she is moving the image captured by the camera140. In particular, the Surgeon is provided with the sensation that heor she is grasping the image being displayed on the monitor 104 with hisor her left and right hands and moving the image about the work site toa desired viewing point.

FIG. 13 illustrates, as an example, a reference frame 400 andcorresponding degrees-of-freedom for controlling movement of a tip ofthe camera 140. In this case, the camera tip 141 may be pivoted about apivot point 410 (also referred to as a “fulcrum” and “remote center”) inroll 421 about an axis X_(C) extending along a longitudinal axis 145 ofthe camera 140 and/or its entry guide (not shown), in pitch 422 about anaxis Y_(C) (which is orthogonal to the X_(C) axis), and in yaw 423 aboutan axis Z_(C) (which is orthogonal to both the X_(C) and Y_(C) axes), aswell as inserted/retracted 424 along the longitudinal axis 145 byoperation of the camera manipulator 212 so as to provide fourdegrees-of-freedom movement. The longitudinal axis 145 centrally extendsthrough the proximal and distal ends of the camera 140. A focal point142 of the camera 140 moves along a surface of a sphere (having a radiusdefined by the insertion distance of the camera tip 141 from the remotecenter 410 and the focal length) as the camera tip 141 is moved in pitchand yaw (i.e., along arc 432 when the camera tip 141 is moved in pitch422 and along arc 433 when the camera tip 141 is moved in yaw 423).

To control movement in the four degrees-of-freedom of the camera tip141, a “virtual handlebar” scheme using the pair of master controls 108,109 is used in which the two master controls are constrained to movetogether in a prescribed manner. Referring to FIG. 12, the “virtualhandlebar” employs a reference frame 300 having its origin at amid-point 320 which is half-way between the pivot points 302, 312 of themaster controls 108, 109. The Y-axis Y_(MP) of the frame 300 is along aline intersecting the pivot points 302, 312, the Z-axis Z_(MP) is in avertical direction orthogonal to the Y-axis Y_(MP), and the X-axisX_(MP) is in a forward/back direction that is orthogonal to both theY-axis Y_(MP) and the Z-axis Z_(MP).

The “virtual handlebar” reference frame 300 is related to the cameracontrol reference frame 400 so that movement relative to the mid-point320 by the master controls 108, 109 results in movement of the cameratip 141 relative to the remote center 410. In particular, as themid-point 320 is moved forward/back in the X_(MP) direction by movingboth master controls 108, 109 forward/back, the camera controller 213commands the camera manipulator 212 to move the camera 140 forward/backin the X_(C) direction. Also, as the left master control 108 is movedup/down and the right master control 109 is moved in an oppositedirection relative to the Z_(MP) axis, the camera controller 213commands the camera manipulator 212 to rotate the camera 140 in rollabout the X_(C) axis. Further, as the left master control 108 is movedforward/back and the right master control 109 is moved in an oppositedirection relative to the X_(MP) axis, the camera controller 213commands the camera 140 to rotate in yaw about the Z_(C) axis. Finally,as both the left and right master controls 108, 109 are pivoted togetherabout their respective pivot points 302, 312 in the same direction, thecamera controller 213 commands the camera manipulator 212 to rotate thecamera 140 in pitch about the Y_(C) axis.

Note that in using the “virtual handlebar” scheme as described abovethere are several unused degrees-of-freedom for each of the mastercontrols 108, 109. For example, the master roll for each master controlis unused (i.e., rotation of its gripper about its X-axis). Since thegripper's master roll resembles a dial to the Surgeon, it potentiallycan be used to turn on and adjust an attribute of an image capturingdevice such as a camera's focus, zoom, brightness, contrast, etc., in asimilar manner as a radio's volume dial may turn on the radio and adjustits volume. Thus, each gripper's master roll may be used as one of thecontrol elements 1011, 1012, 1013, 1021, 1022, 1023. In this case, forcefeedback to the masters may be provided to serve as haptic feedback tothe user to assist the user in manually adjusting the control element.Further, the imaging system 1000 may be implemented in the medicalrobotic system 7000 by the endoscope 37 functioning as the imagecapturing device 1010, the stereo vision display 45 functioning as theviewer 1020, and the processor 43 functioning as the processor 1030.

Although the various aspects of the present invention have beendescribed with respect to a preferred embodiment, it will be understoodthat the invention is entitled to full protection within the full scopeof the appended claims.

What is claimed is:
 1. A method for intelligent manual adjustment of acontrol element, the method comprising: determining a depth value of atarget area relative to the image capturing device; determining adesirable adjustment to a control element for controlling an imagecharacteristic of one of the image capturing device and the viewer byusing the determined depth value, wherein the viewer is displayingimages derived from the image capturing device; and controllingadjustment of the control element to assist manual adjustment of thecontrol element to the desirable adjustment.
 2. The method of claim 1,further comprising: determining whether the adjustment of the controlelement is to be automatically or manually adjusted; and controllingadjustment of the control element automatically to the desirableadjustment if the control element is to be automatically adjusted. 3.The method of claim 1, further comprising: determining the depth valueas one of an average depth value and a minimum depth value for a surfacetopology of the target area.
 4. The method of claim 1, whereindetermining the desirable adjustment to the control element uses atleast one of a plurality of depth values determined for a plurality oftarget areas relative to the image capturing device.
 5. The method ofclaim 1, further comprising: determining a desirable adjustment to asecond control element of a second image capturing device by using adepth value of the target area relative to the second image capturingdevice; determining whether the adjustment of the second control elementis to be automatically or manually adjusted; controlling adjustment ofthe second control element automatically to the desirable adjustment ofthe second control element if the second control element is to beautomatically adjusted and controlling adjustment of the second controlelement to assist manual adjustment of the second control element if thesecond control element is to be manually adjusted; and displaying imagesderived from the second image capturing device along with or switchablywith images derived from the image capturing device on the viewer. 6.The method of claim 1, wherein the control element controls acharacteristic of an image captured by the image capturing device or theimage displayed on the viewer.
 7. The method of claim 6, wherein thecharacteristic comprises one of brightness, focus, contrast, resolution,color balance, sharpness, and other controllable characteristic of theimage captured by the image capturing device or the image displayed onthe viewer.
 8. The method of claim 1, wherein the image capturing deviceis a camera and the control element is a brightness control, and thedetermining the desirable adjustment of the control element comprises:determining the desirable adjustment to the brightness control so that abrightness level of images captured by the camera is lowered if thedepth value of the target area relative to the camera is less than athreshold depth value.
 9. The method of claim 8, wherein the brightnesscontrol is coupled to one of an adjustable gain of an image sensor ofthe camera and an adjustable power output for an illuminator of thecamera.
 10. The method of claim 8, wherein the adjustment to thebrightness control is determined to be such that the brightness levelmonotonically decreases as the depth value changes from the thresholddepth value to a minimum depth value.
 11. The method of claim 10,wherein a rate that the brightness level monotonically decreases as thedepth value changes from the threshold depth value to the minimum depthvalue is a function of a characteristic of an image captured by thecamera.
 12. The method of claim 8, wherein the threshold distance is afunction of a characteristic of an image captured by the camera.
 13. Themethod of claim 1, wherein the target area is a default area unlessoverridden by an operator specified area.
 14. The method of claim 13,wherein the operator specified area is specified by an operator gazingfor a specified period of time at a gaze point on the viewer upon whichimages derived from the image capturing device are being displayed. 15.The method of claim 14, wherein the target area and the depth value ofthe target area relative to the image capturing device are determined bytranslating a specified area about the gaze point on the viewer to thetarget area in a reference frame of the image capturing device.
 16. Themethod of claim 15, further comprising: displaying an indicator of theoperator specified area on the viewer.
 17. The method of claim 14,wherein the image capturing device is a stereo camera and the methodfurther comprises: determining the depth value by applying a sparseimage mapping algorithm on the target area in captured stereo imagesreceived from the stereo camera.
 18. The method of claim 1, wherein theimage capturing device is a camera and the control element is a focuscontrol, and the determining the desirable adjustment to the controlelement comprises: determining the desirable adjustment to the focuscontrol as a function of a focal point of the camera and the depth valueof the target area relative to the camera.
 19. The method of claim 18,further comprising: determining a direction of the adjustment of thecontrol element by determining movement of the camera in a directiontowards or away from the target area.
 20. The method of claim 19,wherein the camera is movable by a robotic arm, and the determining ofthe movement of the camera comprises: receiving sensor informationindicating positions of joints of the robotic arm; and determining themovement of the camera by applying the sensor information to forwardkinematics of the robotic arm.
 21. The method of claim 18, wherein thefocus control is a manually rotatable control; wherein the determiningthe desirable adjustment to the control element comprises determining adirection and an amount that the focal point of the camera is to bemoved in order to coincide with the depth value of the target area; andwherein the controlling adjustment of the control element to assistmanual adjustment of the control element to the desirable adjustmentcomprises providing assistance to adjust the focus control according tothe determined direction and amount.
 22. The method of claim 21, whereinthe providing assistance to adjust the focus control comprises: defininga rotation direction of the manually rotatable control to alwayscorrespond to moving the focal point towards the depth value of thetarget area and an opposite rotation direction of the manually rotatablecontrol to always correspond to moving the focal point away from thedepth value of the target area.
 23. The method of claim 21, wherein theproviding assistance to adjust the focus control comprises: defining arotation direction of the manually rotatable control in which themanually rotatable control is first rotated as corresponding to movingthe focal point towards the depth value of the target area and anopposite rotation direction of the manually rotatable control ascorresponding to moving the focal point away from the depth value of thetarget area.
 24. The method of claim 21, wherein the providingassistance to adjust the focus control comprises: providing a sensoryindication when the focal point of the camera coincides with the targetpoint, wherein the sensory indication is one or more of a visualindication on the viewer upon which images derived from the camera arebeing displayed, an auditory indication, and a force feedback on themanually rotatable control.
 25. The method of claim 24, wherein theforce feedback is a haptic force on the manually rotatable control thatnudges an operator of the manually rotatable control towards the amountthat the focal point of the camera is to be moved in order to coincidewith the depth value of the target area.
 26. The method of claim 25,wherein the haptic force decreases as the focal point of the cameramoves towards the depth value of the target area and increases as thefocal point of the camera moves away from the depth value of the targetarea.
 27. The method of claim 1, wherein the determining of thedesirable adjustment to the control element of one of the imagecapturing device and the viewer uses a look-up table indexed by depthvalues relative to the image capturing device.
 28. The method of claim27, wherein the determining the desirable adjustment to the controlelement comprises processing the information read from the look-up tableby adjusting the information according to predefined operatorpreferences.
 29. The method of claim 1, further comprising: determininga characteristic of an image captured by the image capturing device;wherein the determining the desirable adjustment to the control elementincludes modulating an output of a function of the depth value of thetarget area by the determined characteristic.
 30. An imaging systemcomprising: an image capturing device; a viewer displaying imagesderived from the image capturing device; a control element forcontrolling an image characteristic of one of the image capturing deviceand the viewer; a processor programmed to: determine a depth value of atarget area relative to the image capturing device; determine adesirable adjustment to the control element by using the determineddepth value; and control adjustment of the control element to assistmanual adjustment of the control element to the desirable adjustment.31. The imaging system of claim 30, wherein the processor is programmedto: determine whether the adjustment of the control element is to beautomatically or manually adjusted; and control adjustment of thecontrol element automatically to the desirable adjustment if the controlelement is to be automatically adjusted.
 32. The imaging system of claim30, wherein the processor is programmed to determine the depth value asan average depth value for a surface topology of the target area. 32.The imaging system of claim 30, wherein the control element controls acharacteristic of an image captured by the image capturing device or theimage displayed on the viewer.
 33. The imaging system of claim 32,wherein the characteristic comprises one of brightness, focus, contrast,resolution, color balance, sharpness, and other controllablecharacteristic of the image captured by the image capturing device orthe image displayed on the viewer.
 34. The imaging system of claim 30,wherein the image capturing device is a camera and the control elementis a brightness control, and the processor is programmed to determinethe desirable adjustment of the control element by determining thedesirable adjustment to the brightness control so that a brightnesslevel of images captured by the camera is lowered if the depth value ofthe target area relative to the camera is less than a threshold depthvalue.
 35. The imaging system of claim 34, wherein the brightnesscontrol is coupled to one of an adjustable gain of an image sensor ofthe camera and an adjustable power output for an illuminator of thecamera.
 36. The imaging system of claim 30, wherein the target area is adefault area unless overridden by an operator specified area.
 37. Theimaging system of claim 36, wherein the operator specified area isspecified by an operator gazing for a specified period of time at a gazepoint on the viewer upon which images derived from the image capturingdevice are being displayed.
 38. The imaging system of claim 37, whereinthe target area and the depth value of the target area relative to theimage capturing device are determined by translating a specified areaabout the gaze point on the viewer to the target area in a referenceframe of the image capturing device.
 39. The imaging system of claim 38,wherein the processor is programmed to cause displaying an indicator ofthe operator specified area on the viewer.
 40. The imaging system ofclaim 37, wherein the image capturing device is a stereo camera, andwherein the processor is programmed to determine the depth value byapplying a sparse image mapping algorithm on the target area in capturedstereo images received from the stereo camera.
 41. The imaging system ofclaim 30, wherein the image capturing device is a camera and the controlelement is a focus control, and wherein the processor is programmed todetermine the desirable adjustment to the control element by determiningthe desirable adjustment to the focus control as a function of a focalpoint of the camera and the depth value of the target area relative tothe camera.
 42. The imaging system of claim 41, wherein the processor isprogrammed to determine a direction of the adjustment of the controlelement by determining movement of the camera in a direction towards oraway from the target area.
 43. The imaging system of claim 42, whereinthe camera is movable by a robotic arm and the processor is programmedto determine the movement of the camera by receiving sensor informationindicating positions of joints of the robotic arm and determining themovement of the camera by applying the sensor information to forwardkinematics of the robotic arm.
 44. The imaging system of claim 43,wherein the focus control is a manually rotatable control, wherein theprocessor is programmed to determine the desirable adjustment to thecontrol element by determining a direction and an amount that the focalpoint of the camera is to be moved in order to coincide with the depthvalue of the target area; and wherein the processor is programmed tocontrol adjustment of the control element to assist manual adjustment ofthe control element to the desirable adjustment by providing assistanceto adjust the focus control according to the determined direction andamount.
 45. The imaging system of claim 44, wherein the processor isprogrammed to provide assistance to adjust the focus control by defininga rotation direction of the manually rotatable control to alwayscorrespond to moving the focal point towards the depth value of thetarget area and an opposite rotation direction of the manually rotatablecontrol to always correspond to moving the focal point away from thedepth value of the target area.
 46. The imaging system of claim 44,wherein the processor is programmed to provide assistance to adjust thefocus control by defining a rotation direction of the manually rotatablecontrol in which the manually rotatable control is first rotated ascorresponding to moving the focal point towards the depth value of thetarget area and an opposite rotation direction of the manually rotatablecontrol as corresponding to moving the focal point away from the depthvalue of the target area.
 47. The imaging system of claim 44, whereinthe processor is programmed to provide assistance to adjust the focuscontrol by providing a sensory indication when the focal point of thecamera coincides with the target point, wherein the sensory indicationis one or more of a visual indication on the viewer upon which imagesderived from the camera are being displayed, an auditory indication, anda force feedback on the manually rotatable control.
 48. The imagingsystem of claim 47, wherein the force feedback is a haptic force on themanually rotatable control that nudges an operator of the manuallyrotatable control towards the amount that the focal point of the camerais to be moved in order to coincide with the depth value of the targetarea.
 49. The imaging system of claim 30, wherein the processor isprogrammed to determine the desirable adjustment of the control elementby using a look-up table indexed by depth values relative to the imagecapturing device.
 50. The imaging system of claim 30, wherein theprocessor is programmed to determine a characteristic of an imagecaptured by the image capturing device, and wherein the processor isprogrammed to determine the desirable adjustment to the control elementby modulating an output of a function of the depth value of the targetarea by the determined characteristic.